What's the hardest engineering challenge you've ever solved?

"The loop ran for 2+ months and ended up being six to seven rounds with no take-home: recruiter screen, hiring managers, case-heavy interviews, and separate behaviorals. No take-home, surprisingly! Almost every round blended casing and behavioral, so it never felt like I could fully switch my brain off one side or the other. The interviews themselves were candidate-led, with one interviewer feeling super collaborative and another much more reserved and watchful, especially in the cases. I feel like the biggest theme across the whole process was that LinkedIn cared a lot about story, stakeholder management, and whether I was actually AI-native versus just saying buzzwords."